Do I need fast reflexes to play the Telltale game "Game of Thrones"?
Solution 1:
From personal experience, game of thrones' QTEs (quick time events, often requiring the press of a button or directional input within a smallish timeframe to carry out actions ingame) aren't as intense as The Walking Dead and other Telltale games. Combat in Telltale's Game Of Thrones isn't like full-on mouse controlled attacking and blocking, just simple QTEs. Although sometimes you might need fairly quick reflexes (probably about a 3 second window to pull off a QTE), if you fail it, you're put right before it, and now since you know where and what it is and it should be easier to perform. If the QTEs are a deal breaker for you, you should know within the first two hours, and if you're buying on steam you should be able to refund it if that's the case.
Solution 2:
Having played through on the Xbox One version, I found that the quick time events (QTEs) are infrequent. Most of your interactions will be choosing what to say. Note that you have a small window for these options before you automatically give a no response/default response during dialogue.
With the QTEs, you go through a simple sequence of anywhere from 1 to around 5 actions. You have a small window and most of the patterns repeat if you fail (although sometimes the buttons to press can change). If you fail you are almost always taken back to the start of the QTE.
Some of the QTEs may involve mild button mashing. It isn't too demanding but be aware if this will cause you problems.